The use of electromagnetic impedance measurement devices to secure physical properties of a material under test with a planar electrode sensor array have been identified in U.S. Pat. Nos. 5,900,736, 6,400,161, 6,414,497, and 7,219,024, each of which is hereby incorporated by reference in its entirety. The apparatus covered in U.S. Pat. Nos. 5,900,736, 6,414,497, and 7,219,024, use a planar concentric electrode array to secure data about a MUT. US Patent Publication No. 2012/0013354 (hereby incorporated by reference in its entirety) also presents a planar concentric electrode array and terms it a “concentric coplanar capacitive sensor”. The planar concentric electrode arrays fall under a class of electronics that is termed “coplanar wave guides.” While there are a number of advantages in using the concentric electrode array, this array also has limitations. A first limitation is that the concentric electrode array is not readily conducive to providing tomographic information. The use of electromagnetic magnetic tomographic and spectrographic measurement devices, which have been identified in US Patent Publication Nos. 2009/0170756 and 2012/0130212 (each of which is hereby incorporated by reference in its entirety), and U.S. Provisional Patent Application Nos. 61/647,848 and 61/703,488 (each of which is hereby incorporated by reference in its entirety), address the issue of locating specified volumes within an MUT and characterizing that volume based upon its electromagnetic characteristics. A second limitation of the concentric electrode array is that the size of the electrode array limits the potential depth of evaluation into the MUT. In general, the maximum depth that can be evaluated is at best equal to one half of the sensor diameter, and in practice, the depth is even less.
The embodiments of the designs for the planar electrode array presented in the application provide for a means to address the second limitations. The art presented in US Patent Publications 2009/0170756 and 2012/0130212 and Applications 61/647,848 and 61/703,488 address the first limitation.